INHIBITORY EFFECTS OF DIALLYL DISULFIDE OR ASPIRIN ON NO-1-METHYL-6-PHENYLIMIDAZO[4,5-B]PYRIDINE-INDUCED MAMMARY CARCINOGENESIS IN RATS

Modifying effects of diallyl disulfide (DAD), aspirin or DL-alpha-difl uoromethylornithine (DFMO) on 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP)-induced mammary carcinogenesis in SD rats were investi gated. A total of 166 female rats, 6 weeks old, were divided into 8 gr oups. They were fed a high fat diet throughout the experiment. Startin g at 7 weeks of age, groups 1-4 were given PhIP (85 mg/kg body weight in corn oil) by gavage 8 times in 10 days, and groups 5-8 were given c orn oil alone. For the beginning 4 weeks, groups 2 and 5 were given DA D at 200 ppm in diet. Similarly groups 3 and 6, and groups 4 and 7 wer e given aspirin (400 ppm) and DFMO (400 ppm), respectively. Mammary ca rcinomas were only recognized in groups 1-4 at the termination (25 wee ks after the start of experiment). Multiplicity (mean number/rat) of n eoplasms in group 2 (PhIP+DAD, 0.90/rat) and group 3 (PhIP+aspirin, 1. 37/rat) was significantly smaller than that in group 1 (PhIP alone, 2. 45/rat) (P < 0.005 and P < 0.05, respectively). These results indicate that dietary intake of DAD or aspirin during the time corresponding t o initiation phase has chemopreventive potential on PhIP-induced mamma ry carcinogenesis in rats.